Data Views Total Plants: 2 CSV Excel PDF Total Activities: 1 Click on column headings to sort table by that column Plant Part All Bark Stem Bark Low PPM High PPM StdDev *Reference Rhamnus cathartica Stem Bark -- 360.0 * Frangula purshiana Bark -- -- * *Unless otherwise noted all references are to Duke, James A. 1992. Handbook of phytochemical constituents of GRAS herbs and other economic plants. Boca Raton, FL. CRC Press.